Optical Alignment System for Beam Pumping Unit

ABSTRACT

An optical alignment system is configured to determine lateral and longitudinal offset between a pump jack and a wellhead. The optical alignment system includes a target assembly that is configured to be secured to the pump jack. The target assembly includes a target that faces the wellhead. The optical alignment system further includes an emitter assembly that is configured to be secured directly or indirectly to the wellhead. The emitter assembly includes an emitter that is configured to project one or more visible lines onto the target.

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/422,337 filed Feb. 1, 2017, entitled “Optical Alignment System forBeam Pumping Unit,” which issued as U.S. Pat. No. 10,590,725 on Mar. 17,2020, and which claims the benefit of U.S. Provisional PatentApplication Ser. No. 62/290,675, filed Feb. 3, 2016, entitled “BeamPumping Unit Laser Alignment,” the disclosures of which are herebyincorporated by reference.

FIELD OF THE INVENTION

This invention relates generally to oilfield equipment, and moreparticularly, but not by way of limitation, to a system and method foraligning a beam pumping unit over a wellhead.

BACKGROUND

Hydrocarbons are often produced from well bores by reciprocatingdownhole pumps that are driven from the surface by pumping units. Apumping unit is connected to its downhole pump by a rod string. Althoughseveral types of pumping units for reciprocating rod strings are knownin the art, walking beam style pumps enjoy predominant use due to theirsimplicity and low maintenance requirements.

Each beam pump unit should be positioned so that the horsehead isproperly positioned above the production tubing. This allows the bridleto travel vertically when raising and lowering the sucker rod. Nothaving a horsehead in this position can produce an offset force betweenthe polish rod and the bridle, which may result in wear and increasedfriction between the polish rod and the stuffing box and tee. Onepossible consequence of this offset and friction is that the contents ofthe stuffing box may prematurely wear and deteriorate. If this occursand the stuffing box is not timely repaired, a leak of the productionfluid may develop, possibly causing an environmental hazard.

The alignment between the well bore and the beam pump is typically doneat the time the well is completed and the beam pump is installed.Realignment may be necessary if the pump unit shifts or is serviced. Oneprior art method of performing this alignment involves hanging a plumbbob from the horsehead to find the location of the pump unit relative tothe production tubing. This usually requires the bridle to be pulledaway from the horsehead and the plumb bob string placed in the bridlegroove or at another place on the horsehead above the center of theproduction tubing. An observer then sights the location of the plumb bobrelative to the center of the production tubing.

Although widely adopted, the line suspending the plumb bob is subject tothe vagaries of the weather; a small breeze may have the result ofproducing a misalignment between the horsehead and the center of theproduction tube. Additionally, the resting point of the plumb bob may besubjective to the eye and may not yield a true alignment if the bob isnot unquestionably at a point resting immediately above the center ofthe polish rod. There is, therefore, a need for a cost-effectivesolution for aligning the pump unit with the wellhead that overcomesthese and other deficiencies in the prior art.

SUMMARY OF THE INVENTION

In one aspect, embodiments of the present invention include an opticalalignment system configured to determine lateral and longitudinal offsetbetween a pump jack and a wellhead. The optical alignment systemincludes a target assembly that is configured to be secured to the pumpjack. The target assembly includes a target that faces the wellhead. Theoptical alignment system further includes an emitter assembly that isconfigured to be secured directly or indirectly to the wellhead. Theemitter assembly includes an emitter that is configured to project oneor more visible lines onto the target.

In another aspect, embodiments of the present invention include anoptical alignment system configured to determine lateral andlongitudinal offset between a pump jack and a wellhead, where the pumpjack includes a pump jack base. The optical alignment system includes atarget assembly, and an emitter assembly. The target assembly isconfigured to be secured to the pump jack, and the emitter assembly isconfigured to be secured directly or indirectly to the wellhead.

In yet another aspect, embodiments of the present invention include anoptical alignment system that is configured to determine lateral andlongitudinal offset between a pump jack and a wellhead, where the pumpjack includes a pump jack base. The optical alignment system has atarget assembly that is configured to be secured to the pump jack. Theoptical alignment system further includes means for displaying visualindicators on the target assembly that are indicative of the lateral andlongitudinal alignment of the pump jack base with the wellhead.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a beam pumping unit operating on a well.

FIG. 2 depicts the pumping unit of FIG. 1 during an alignment procedure.

FIG. 3 is a front view of the target assembly.

FIG. 4 is a bottom view of the target assembly of FIG. 3.

FIG. 5 is a top view of the emitter assembly.

FIG. 6 is a side view of the emitter assembly of FIG. 5.

FIG. 7 is a perspective view of a chain clamp assembly connected to thebody of the emitter assembly of FIG. 5.

FIG. 8 is a depiction of the cooperative use of the emitter assembly andtarget assembly for a lateral alignment operation.

FIG. 9 is a depiction of the cooperative use of the emitter assembly andthe target assembly for a longitudinal alignment operation.

FIG. 10 is a flowchart depicting a pump-wellhead alignment method.

WRITTEN DESCRIPTION

FIG. 1 shows a class 1 beam pump jack 100. The pump jack 100 is drivenby a prime mover 102, typically an electric motor or internal combustionengine. The rotational power output from the prime mover 102 istransmitted by a drive belt 104 to a gearbox 106. The gearbox 106provides low-speed, high-torque rotation of a crankshaft 108. Each endof the crankshaft 108 (only one is visible in FIG. 1) carries a crankarm 110 and a counterbalance weight 112. The reducer gearbox 106 sitsatop a sub-frame or pedestal 114, which provides clearance for the crankarms 110 and counterbalance weights 112 to rotate. The gearbox pedestal114 is mounted atop a base 116. The base 116 also supports a Samson post118. The top of the Samson post 118 acts as a fulcrum that pivotallysupports a walking beam 120 via a saddle bearing assembly 122, commonlyreferred to as a center bearing assembly.

Each crank arm 110 is pivotally connected to a pitman arm 124 by a crankpin bearing assembly 126. The two pitman arms 124 are connected to anequalizer bar 128, and the equalizer bar 128 is pivotally connected tothe rear end of the walking beam 120 by an equalizer bearing assembly130. A horsehead 132 with an arcuate forward face 134 is mounted to theforward end of the walking beam 120. The face 134 of the horsehead 132interfaces with a flexible wire rope bridle 136. At its lower end, thebridle 136 terminates with a carrier bar 138, upon which a polish rod140 is suspended.

The polish rod 140 extends through a packing gland or stuffing box 142on a wellhead 144. A rod string 146 of sucker rods hangs from the polishrod 140 within a tubing string 148 located within the well casing 150.The rod string is connected to the plunger of a subsurface pump (notillustrated). In a reciprocating cycle of the pump jack 100, well fluidsare lifted within the tubing string 148 during the rod string 146upstroke. It will be appreciated that the pump jack 100 depicted in FIG.1 is merely an exemplar and is not intended to limit the scope of thealignment system and method described in this disclosure.

Turning to FIG. 2, shown therein is the pump jack 100 from FIG. 1undergoing an installation or adjustment procedure using an opticalalignment system 152. Generally, the optical alignment system 152 isused to determine the extent of alignment between the pump jack 100 andthe polish rod 140 when it is positioned within the wellhead 144. Basedon information provided by the optical alignment system 152, the pumpjack 100 can be moved longitudinally and laterally so that the pump jack100 is properly aligned with the wellhead 144. As used in thisdisclosure, the term “longitudinal” refers to movement or distance alongthe line extending between the pump jack 100 and the wellhead 144. Theterm “lateral” refers to movement or distance along a line that isperpendicular to the longitudinal axis. It will be understood that thelongitudinal and lateral axes each constitute a major axis.

The optical alignment system 152 includes two primary components: atarget assembly 154 and an emitter assembly 156. In exemplaryembodiments, the emitter assembly 156 is attached to the polish rod 140.The target assembly 154 is connected to the arcuate forward face 134 ofthe horsehead 132. As noted in FIG. 1, the bridle 136 has been removedfrom the horsehead 144 to better illustrate the form and function of theoptical alignment system 152.

Turning to FIGS. 3 and 4, shown therein are front and bottom views,respectively, of the target assembly 154 as installed on the horsehead132 (partially shown). The target assembly 154 includes a target 158connected to a body 160. The target assembly 154 also includes a pair ofclamps 162 that are configured for opposite movement within the body 160in response to the manipulation of an adjustment crank 164. In theexemplary embodiment depicted in FIGS. 3 and 4, turning the adjustmentcrank 164 rotates a threaded rod 166 that causes the clamps 162 to movein opposite directions. As best shown in FIG. 4, the clamps 162 aresized and configured to grasp the outside of the horsehead 132, with thetarget 158 facing down toward the wellhead 144. The simultaneous,coordinated movement of the clamps 162 centers the target assembly 154on the horsehead 132.

The target assembly 154 may also include a support ring 166 connected tothe body 160. The support ring 166 can be used to tether the targetassembly 154 to the horsehead 132 with a cable or wire rope. The targetassembly 154 optionally includes levels 168 that can be used to ensurethat the target assembly 154 is positioned in a horizontal position onthe horsehead 132. In some embodiments, the target assembly 154 isplaced on the horsehead 132 just below the apex of the arcuate forwardface 134.

The target 158 may include reference markings that indicate thelongitudinal and lateral axes between the pump jack 100 and the wellhead144. The target assembly 154 is secured to the horsehead 132 in a levelorientation where the center of the target 158 is located along the samevertical axis that would pass through the polish rod 140 when it issuspended from the horsehead 132 by the bridle 136 and carrier bar 138.In some embodiments, the target 158 includes a level (not shown) thatcan be used to ensure that the target 158 is oriented in a horizontalplane that is perpendicular to the vertical axis extending through thecenter of the polish rod 140.

Turning to FIGS. 5 and 6, shown therein are top and side views,respectively, of the emitter assembly 156. The emitter assembly 156includes a base 170, an emitter 172 and emitter supports 174. The base170 includes an aperture 176 that is configured to admit the polish rod140. In the embodiment depicted in FIGS. 5 and 6, the base 170 isseparated into two parts that are connected with fasteners 178.Tightening the fasteners clamps the base 170 around the polish rod 140(as best seen in FIG. 6). A bushing 180 can be placed into the aperture176 to provide a better fit and grip between the base 170 and the polishrod 140. It will be understood that the lower portion of the polish rod140 is rigidly captured within the wellhead 144 during this operation sothat the upper portion of the polish rod 140 provides a stable base fromwhich to suspend the emitter assembly 156. In this position, the polishrod 140 provides an indication and reference for the center of thetubing string 148.

The emitter 172 that is configured to project one or more visible linesonto the target 158. In exemplary embodiments, the emitter 172 isconfigured to simultaneously emit laser light in two directions, witheach emission configured to produce a continuous visible line along thehorizontal and vertical axes. Suitable laser emitters are available fromPacific Laser Systems, a division of Fluke Electronics, under the “PLS180” brand. The emitter 172 may optionally be fitted with aself-leveling system that ensures that the lasers are emitted insubstantially vertical and horizontal planes. The emitter 172 issupported by the base 170 and captured between the emitter supports 174.It will be appreciated that other optical targeting systems may be usedin addition to, or as an alternative to, the emitter. For example,point-to-point laser systems may be used in place of the line systemsdescribed above. In another embodiment, two emitters 172 may be mountedon the base 170 at an angle apart to deliver a crosshair beam above thepolish rod 140. In other embodiments, the emitter 172 is configured toproject non-laser light onto the target 158.

Turning to FIG. 7, shown therein is a perspective view of the emitterassembly 156 and chain clamp 182. The chain clamp 182 provides analternate mechanism for securing the emitter assembly 156 to thewellhead 144. The chain clamp 182 includes a V-block 184, a chain 186, achain tensioner 188 and support brackets 190. The V-block 184 is sizedand configured to be pressed against a cylindrical portion of thewellhead 144. The chain tensioner 188 includes a clasp 192 and anadjustment dial 194. The support brackets 190 are releasably secured thebody 160 of the emitter assembly 156. It will be appreciated that theemitter assembly 156 can be secured to the chain clamp 182 with thesupport brackets 190 before or after the chain clamp 182 is secured tothe wellhead 144.

During use, a first end of the chain 186 is secured within theadjustment dial 194. The second end of the chain 186 is wrapped aroundthe wellhead 144 and placed into the clasp 192 with a modest amount oftension applied by hand. The chain 186 is then tightened by turning theadjustment dial 194 to move the first end of the chain 186 away from theV-block 184, which increases the distance between the captured end ofthe chain 186 within the clasp 192 and adjustment dial 194. The tensionsupplied by the chain 186 presses the V-block 184 against the side ofthe wellhead 144, thereby providing a stable base on which the emitterassembly 156 can be suspended. The use of chain clamp 182 isparticularly beneficial in applications in the pump jack 100 is beinginstalled on a new wellhead 144 or in other situations in which thepolish rod 140 is not present.

Turning to FIGS. 8 and 9, shown therein are graphic representations ofan alignment procedure carried out with the optical alignment system152. In FIG. 8, the emitter assembly 156 has been connected to thepolish rod 140 such that the vertical laser produces a line that runssubstantially parallel to the longitudinal axis to the pump jack 100. Inthis position, the emitter 172 casts a line that contacts the target 158and provides an indication of the lateral position of the pump jack 100with respect to the center of the polish rod 140. The laser-lineindication on the target 158 in FIG. 8 indicates that the pump jack 100should be shifted slightly to the right (when looking at the wellhead144 from the pump jack 100).

In FIG. 9, the emitter assembly 156 has been rotated 90° on the polishrod 140 such that the vertical laser produces a line that runssubstantially parallel to the lateral axis between the pump jack 100 andthe wellhead 144. In this position, the emitter 172 paints a line thatcontacts the target 158 and provides an indication of the longitudinalposition of the pump jack 100 with respect to the center of the polishrod 140. The laser-line indication on the target 158 in FIG. 9 indicatesthat the pump jack 100 should be shifted slightly forward toward thewellhead 144.

Thus, the optical alignment system 152 can be used to rapidly, reliablyand accurately provide an indication of the alignment between the pumpjack 100 and the wellhead 144. Turning to FIG. 10, shown therein is anexemplary embodiment of a method 200 for aligning the pump jack 100 withthe wellhead 144. At step 202, the target assembly 154 is attached tothe horsehead 132 of the pump jack 100. During this step, the targetassembly 154 is secured to the horsehead 132 in a level orientationwhere the center of the target 158 is located along the same verticalaxis that would pass through the polish rod 140 when it is suspendedfrom the horsehead 132 by the bridle 136 and carrier bar 138.

Next, at step 204, the emitter assembly 156 is secured to the polish rod140. During this step, the base 170 of the emitter assembly 156 istightened around the polish rod 140 and the emitter 172 is securedbetween the emitter supports 174. If necessary, a bushing 180 is placedwithin the aperture 176 before the base 170 is placed over or onto thepolish rod 140.

The method 200 continues at step 206, where the emitter assembly 156 ismoved to a first position to determine the lateral alignment between thepump jack 100 and the wellhead 144. The emitter assembly 156 isactivated and draws a continuous laser line that is substantiallyparallel with the longitudinal axis between the pump jack 100 and thewellhead 144 (as illustrated in FIG. 8).

At decision step 208, a visual determination is made about whether thepump jack 100 is laterally aligned with the polish rod 140 and wellhead144. If not, the method 200 moves to step 210 and the lateral positionof the pump jack 100 is adjusted. The method 200 then returns to step206 and the steps of measuring and adjusting the lateral position of thepump jack 100 are repeated until proper alignment is achieved. At thatpoint, the method 200 passes to step 212, where the emitter assembly 156is rotated approximately 90° to a second position.

In the second position, the emitter assembly 156 emits a vertical, linethat is substantially parallel to the lateral axis extending between thepump jack 100 and the wellhead 144 (as illustrated in FIG. 9). Atdecision step 214, a visual determination is made about whether the pumpjack 100 is longitudinally aligned with the polish rod 140 and wellhead144. If not, the method 200 moves to step 216 and the longitudinalposition of the pump jack 100 is adjusted. The method 200 then returnsto step 212 and the steps of measuring and adjusting the longitudinalposition of the pump jack 100 are repeated until proper alignment isachieved. At that point, the method 200 passes to step 218, where theoptical alignment system 152 is removed from the pump jack 100 andpolish rod 140. The position of the pump jack 100 can then be fixed andthe installation of the pump jack 100 completed.

In an alternate embodiment, the longitudinal alignment between the pumpjack 100 and the wellhead 144 is established before evaluating thelateral alignment. Thus, steps 212, 214 and 216 could be exchanged withsteps 206, 208 and 210 within the method 200. The order of steps canoccur in a variety of sequences unless otherwise specifically limited.The various steps described herein can be combined with other steps,interlineated with the stated steps, and/or split into multiple steps.It will be further understood that the method 200 can take place duringthe initial installation of the pump jack 100 or during a maintenanceoperation following the initial installation.

Elements have been described functionally and can be embodied asseparate components or can be combined into components having multiplefunctions. The inventions have been described in the context ofpreferred and other embodiments and not every embodiment of theinvention has been described. Obvious modifications and alterations tothe described embodiments are available to those of ordinary skill inthe art. The disclosed and undisclosed embodiments are not intended tolimit or restrict the scope or applicability of the invention conceivedof by the Applicant, but rather, in conformity with the patent laws,Applicant intends to fully protect all such modifications andimprovements that come within the scope or range of equivalent of thefollowing claims.

It is to be understood that even though numerous characteristics andadvantages of various embodiments of the present invention have been setforth in the foregoing description, together with details of thestructure and functions of various embodiments of the invention, thisdisclosure is illustrative only, and changes may be made in detail,especially in matters of structure and arrangement of parts within theprinciples of the present invention to the full extent indicated by thebroad general meaning of the terms in which the appended claims areexpressed. It will be appreciated by those skilled in the art that theteachings of the present invention can be applied to other systemswithout departing from the scope and spirit of the present invention.

What is claimed is:
 1. An optical alignment system configured todetermine lateral and longitudinal alignment between a pump jack and awellhead, wherein the pump jack includes a base, the optical alignmentsystem comprising: a target assembly, wherein the target assembly isconfigured to be secured to the pump jack, wherein the target referencemarkings indicative of the longitudinal and lateral alignment betweenthe pump jack base and the wellhead; and an emitter assembly, whereinthe emitter assembly is directly or indirectly to the wellhead.
 2. Theoptical alignment system of claim 1, wherein the emitter assembly isrotatably mounted to the wellhead and configured for rotation between afirst position used to evaluate the lateral alignment between the pumpjack base and the wellhead and a second position used to evaluate thelongitudinal position between the pump jack base and the wellhead. 3.The optical alignment system of claim 2, wherein the emitter assembly isconfigured to emit a first beam of light to project a first line on thetarget assembly when the emitter assembly is secured to the wellhead inthe first position, wherein the first line is indicative of a lateralalignment between the pump jack and the wellhead, and wherein theemitter assembly is configured to project a second beam of light fromthe emitter assembly to project a second line on the target assemblywhen the emitter assembly is rotated about the wellhead to the secondposition, wherein the second line is indicative of a longitudinalalignment between the pump jack and the wellhead.
 4. The opticalalignment system of claim 3, wherein a lower portion of a polish rod isretained within the wellhead and wherein the emitter assembly isconfigured to be secured to an upper portion of the polish rod.
 5. Theoptical alignment system of claim 3, wherein the emitter assemblycomprises a chain clamp configured to secure the emitter assembly to thewellhead.
 6. The optical alignment system of claim 3, wherein theemitter assembly comprises: a base; and an emitter supported by thebase.
 7. The optical alignment system of claim 3, wherein the targetassembly comprises: a body; a pair of opposable and adjustable clampsconnected to the body; and a target supported by the body.
 8. Theoptical alignment system of claim 7, wherein the pump jack includes ahorsehead and the target assembly is configured to be secured to thehorsehead.
 9. The optical alignment system of claim 8, wherein thehorsehead includes an arcuate front face and the target assembly isconfigured to be secured to the horsehead below an apex of the arcuatefront face.
 10. An optical alignment system configured to determinelateral and longitudinal offset between a pump jack and a wellhead,wherein the pump jack includes a pump jack base, the optical alignmentsystem comprising: a target assembly, wherein the target assembly isconfigured to be secured to the pump jack; and an emitter assembly,wherein the emitter assembly is configured to be secured directly orindirectly to the wellhead.
 11. The optical alignment system of claim10, wherein the target assembly comprises: a body; a pair of opposableand adjustable clamps connected to the body; and a target supported bythe body.
 12. The optical alignment system of claim 10, wherein theemitter assembly comprises: a base; and an emitter supported by thebase.
 13. The optical alignment system of claim 12, wherein the emitterassembly is rotatably mounted to the wellhead and configured forrotation between a first position used to evaluate the lateral alignmentbetween the pump jack base and the wellhead and a second position usedto evaluate the longitudinal position between the pump jack base and thewellhead.
 14. The optical alignment system of claim 13, wherein theemitter assembly is configured to emit a first beam of light to projecta first line on the target assembly when the emitter assembly is securedto the wellhead in the first position, wherein the first line isindicative of a lateral alignment between the pump jack and thewellhead, and wherein the emitter assembly is configured to project asecond beam of light from the emitter assembly to project a second lineon the target assembly when the emitter assembly is rotated about thewellhead to the second position, wherein the second line is indicativeof a longitudinal alignment between the pump jack and the wellhead. 15.The optical alignment system of claim 14, wherein a lower portion of apolish rod is retained within the wellhead and wherein the emitterassembly is configured to be secured to an upper portion of the polishrod.
 16. The optical alignment system of claim 14, wherein the emitterassembly comprises a chain clamp configured to secure the emitterassembly to the wellhead.
 17. An optical alignment system configured todetermine lateral and longitudinal offset between a pump jack and awellhead, wherein the pump jack includes a pump jack base, the opticalalignment system comprising: a target assembly, wherein the targetassembly is configured to be secured to the pump jack; and means fordisplaying visual indicators on the target assembly that are indicativeof the lateral and longitudinal alignment of the pump jack base with thewellhead.
 18. The optical alignment system of claim 17, wherein themeans for displaying visual indicators is configured to emit a firstbeam of light to project a first line on the target assembly when theemitter assembly is secured to the wellhead in the first position,wherein the first line is indicative of a lateral alignment between thepump jack and the wellhead, and wherein the emitter assembly isconfigured to project a second beam of light from the emitter assemblyto project a second line on the target assembly when the emitterassembly is rotated about the wellhead to the second position, whereinthe second line is indicative of a longitudinal alignment between thepump jack and the wellhead.
 19. The optical alignment system of claim18, wherein the target assembly comprises: a body; a pair of opposableand adjustable clamps connected to the body; and a target supported bythe body.
 20. The optical alignment system of claim 19, wherein the pumpjack includes a horsehead and the target assembly is configured to besecured to the horsehead.